Insights into ozone deposition patterns from decade-long ozone flux measurements over a mixed temperate forest

2012 ◽  
Vol 14 (6) ◽  
pp. 1684 ◽  
Author(s):  
J. Neirynck ◽  
B. Gielen ◽  
I. A. Janssens ◽  
R. Ceulemans
Keyword(s):  
Temperate Forest ◽  
Deposition Patterns ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
Flux Measurements

scholarly journals Determination of oceanic ozone deposition by ship-borne eddy covariance flux measurements

2010 ◽  
Vol 3 (2) ◽  
pp. 441-455 ◽  
Author(s):  
L. Bariteau ◽  
D. Helmig ◽  
C. W. Fairall ◽  
J. E. Hare ◽  
J. Hueber ◽  
...  
Keyword(s):  
Time Lag ◽  
Fast Response ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
The North ◽  
Flux System ◽  
Deposition Velocities ◽  
Flux Measurements ◽  
Chemical Analyzer

Abstract. A fast response ozone analyzer based on the ozone-nitric oxide chemiluminescence method was integrated into the NOAA-ESRL flux system to achieve the first ship-borne, direct ozone flux measurements over the open ocean. Air was collected from an inlet at 18 m height over the ocean surface mounted to the bow-jackstaff and via a 30 m-long sampling line to the ozone instrument on the ship deck. A "puff" system was used for accurate and regular determination of the sample transport time (lag) between the inlet and the chemical analyzer. A Nafion-membrane dryer facilitated removal of fast water vapor fluctuations, which eliminated the need for quenching and density correction of the ozone signal. The sampling-analyzer system was found to have a ~0.25–0.40 s response time at a sensitivity of ~2800 counts s−1 per ppbv of ozone. Quality control and data filtering procedures for eliminating data that did not meet measurement requirements were critically evaluated. The new ozone flux system was deployed aboard the NOAA Ship Ronald H. Brown, and evaluated using results obtained during several research cruises off the coasts of the North and South America continents, yielding ozone deposition velocities (mean ± standard error) ranging from 0.009±0.001 cm s−1 to 0.24±0.020 cm s−1.

scholarly journals Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

2012 ◽  
Vol 12 (24) ◽  
pp. 12165-12182 ◽  
Author(s):  
Ü. Rannik ◽  
N. Altimir ◽  
I. Mammarella ◽  
J. Bäck ◽  
J. Rinne ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Water Vapour ◽  
Environmental Variables ◽  
Total Ozone ◽  
Explanatory Power ◽  
Growing Season ◽  
Sink Strength ◽  
Ozone Deposition ◽  
Air Space ◽  
Flux Measurements

Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. The canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, with the main focus on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time-scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising the big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s−1) and lowest during winter dormancy (1 mm s−1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained the high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). The set of common environmental variables and terpene concentrations used in multivariate analysis were able to predict the observed average seasonal variation in total and non-stomatal deposition but failed to explain the inter-annual differences, suggesting that some still unknown mechanisms might be involved in determining the inter-annual variability. Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. The results clearly showed the importance of several non-stomatal removal mechanisms. Unknown chemical compounds or processes correlating with monoterpene concentrations, including potentially reactions at the surfaces, contribute to non-stomatal sink term.

scholarly journals Similarity between seed rain and neighbouring mature tree communities in an old-growth temperate forest

2019 ◽  
Vol 31 (6) ◽  
pp. 2435-2444
Author(s):  
Yunyun Wang ◽  
Jalene M. LaMontagne ◽  
Fei Lin ◽  
Zuoqiang Yuan ◽  
Ji Ye ◽  
...  
Keyword(s):  
Seed Dispersal ◽  
Temperate Forest ◽  
Community Dynamics ◽  
Basal Area ◽  
Seed Rain ◽  
Mature Trees ◽  
Data Set ◽  
Deposition Patterns ◽  
Tree Communities ◽  
Tree Traits

Abstract Seed distribution and deposition patterns around parent trees are strongly affected by functional traits and therefore influence the development of plant communities. To assess the limitations of seed dispersal and the extent to which diaspore and neighbouring parental traits explain seed rain, we used a 9-year seed data set based on 150 seed traps in a 25-ha area of a temperate forest in the Changbai Mountain. Among 480,598 seeds belonging to 12 families, 17 genera, and 26 species were identified, only 54% of the species with mature trees in the community were represented in seeds collected over the 9 years, indicating a limitation in seed dispersal. Understory species were most limited; overstory species were least limited. Species with wind-dispersed seed had the least limitation, while the lowest similarity in species richness was for animal-dispersed species followed by gravity-dispersed species; fleshy-fruited species had stronger dispersal limitations than dry-fruited species. Generalized linear mixed models showed that relative basal area had a significant positive effect on seed abundance in traps, while the contribution of diaspore traits was low for nearly all groups. These results suggest that tree traits had the strongest contribution to seed dispersal and deposition for all functional groups examined here. These findings strengthen the knowledge that tree traits are key in explaining seed deposition patterns, at least at the primary dispersal stage. This improved knowledge of sources of seeds that are dispersed could facilitate greater understanding of seedling and community dynamics in temperate forests.

scholarly journals Evaluation of the flux gradient technique for measurement of ozone surface fluxes over snowpack at Summit, Greenland

2011 ◽  
Vol 4 (1) ◽  
pp. 1021-1059
Author(s):  
F. Bocquet ◽  
D. Helmig ◽  
B. A. Van Dam ◽  
C. W. Fairall
Keyword(s):  
Gradient Method ◽  
Deposition Velocity ◽  
Surface Fluxes ◽  
Sensitivity Threshold ◽  
Lower Sensitivity ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
Gradient Technique ◽  
Measurement Height ◽  
Polar Snow

Abstract. A multi-step procedure for investigating ozone surface fluxes over polar snow by the tower gradient method was developed and evaluated. These measurements were then used to obtain four months of turbulent ozone flux data at the Summit research camp located in the center of the Greenland ice shield. Turbulent fluxes were determined by the aerodynamic gradient method incorporating tower measurements of (a) ozone gradients measured by commercial ultraviolet absorption analyzers, (b) ambient temperature gradients using aspirated thermocouple sensors, and (c) wind speed gradients determined by cup anemometers. All gradient instruments were regularly inter-compared by bringing sensors or inlets to the same measurement height. The developed protocol resulted in an uncertainty on the order of 0.1 ppbv for 30-min averaged ozone gradients that were used for the ozone flux calculations. This protocol facilitated a lower sensitivity threshold for the ozone flux determination of −8 × 10−3 μg m−2 s−1, respectively ~0.01 cm s−1 for the ozone deposition velocity for typical environmental conditions encountered at Summit. Uncertainty in the 30-min ozone exchange measurements (evaluated by the Monte Carlo statistical approach) was on the order of 10−2 cm s−1. This uncertainty typically accounted to ~20–100% of the ozone exchange velocities that were determined. These measurements are among the most sensitive ozone deposition determinations reported to date. This flux experiment, deployed at Summit for a period of four months, allowed for measurements of the relatively low ozone uptake rates encountered for polar snow, and thereby the study of their environmental and seasonal dependencies.

scholarly journals Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

2012 ◽  
Vol 12 (5) ◽  
pp. 12715-12758
Author(s):  
Ü. Rannik ◽  
N. Altimir ◽  
I. Mammarella ◽  
J. Bäck ◽  
J. Rinne ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Water Vapour ◽  
Chemical Reactions ◽  
Total Ozone ◽  
Explanatory Power ◽  
Growing Season ◽  
Sink Strength ◽  
Ozone Deposition ◽  
Air Space ◽  
Flux Measurements

Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. Canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, focusing on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time- scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s−1) and lowest during winter dormancy (1 mm s−1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. This was also confirmed by the statistical analysis that did not link measured sesquiterpene concentration with ozone deposition. It was concluded that chemical reactions with monoterpenes, or other removal mechanisms such as surface reactions, play a role as ozone non-stomatal sink inside canopy.

scholarly journals Ozone deposition impact assessments for forest canopies require accurate ozone flux partitioning on diurnal timescales

2021 ◽  
Vol 21 (24) ◽  
pp. 18393-18411
Author(s):  
Auke J. Visser ◽  
Laurens N. Ganzeveld ◽  
Ignacio Goded ◽  
Maarten C. Krol ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Land Surface ◽  
Large Scale ◽  
Crop Yields ◽  
Carbon Sink ◽  
Surface Ozone ◽  
Ozone Uptake ◽  
Ozone Deposition ◽  
Ozone Flux

Abstract. Dry deposition is an important sink of tropospheric ozone that affects surface concentrations and impacts crop yields, the land carbon sink, and the terrestrial water cycle. Dry deposition pathways include plant uptake via stomata and non-stomatal removal by soils, leaf surfaces, and chemical reactions. Observational studies indicate that ozone deposition exhibits substantial temporal variability that is not reproduced by atmospheric chemistry models due to a simplified representation of vegetation uptake processes in these models. In this study, we explore the importance of stomatal and non-stomatal uptake processes in driving ozone dry deposition variability on diurnal to seasonal timescales. Specifically, we compare two land surface ozone uptake parameterizations – a commonly applied big leaf parameterization (W89; Wesely, 1989) and a multi-layer model (MLC-CHEM) constrained with observations – to multi-year ozone flux observations at two European measurement sites (Ispra, Italy, and Hyytiälä, Finland). We find that W89 cannot reproduce the diurnal cycle in ozone deposition due to a misrepresentation of stomatal and non-stomatal sinks at our two study sites, while MLC-CHEM accurately reproduces the different sink pathways. Evaluation of non-stomatal uptake further corroborates the previously found important roles of wet leaf uptake in the morning under humid conditions and soil uptake during warm conditions. The misrepresentation of stomatal versus non-stomatal uptake in W89 results in an overestimation of growing season cumulative ozone uptake (CUO), a metric for assessments of vegetation ozone damage, by 18 % (Ispra) and 28 % (Hyytiälä), while MLC-CHEM reproduces CUO within 7 % of the observation-inferred values. Our results indicate the need to accurately describe the partitioning of the ozone atmosphere–biosphere flux over the in-canopy stomatal and non-stomatal loss pathways to provide more confidence in atmospheric chemistry model simulations of surface ozone mixing ratios and deposition fluxes for large-scale vegetation ozone impact assessments.

scholarly journals Evaluation of the flux gradient technique for measurement of ozone surface fluxes over snowpack at Summit, Greenland

2011 ◽  
Vol 4 (10) ◽  
pp. 2305-2321 ◽  
Author(s):  
F. Bocquet ◽  
D. Helmig ◽  
B. A. Van Dam ◽  
C. W. Fairall
Keyword(s):  
Gradient Method ◽  
Deposition Velocity ◽  
Surface Fluxes ◽  
Sensitivity Threshold ◽  
Lower Sensitivity ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
Gradient Technique ◽  
Measurement Height ◽  
Polar Snow

Abstract. A multi-step procedure for investigating ozone surface fluxes over polar snow by the tower gradient method was developed and evaluated. These measurements were then used to obtain five months (April–August 2004) of turbulent ozone flux data at the Summit research camp located in the center of the Greenland ice shield. Turbulent fluxes were determined by the gradient method incorporating tower measurements of (a) ozone gradients measured by commercial ultraviolet absorption analyzers, (b) ambient temperature gradients using aspirated thermocouple sensors, and (c) wind speed gradients determined by cup anemometers. All gradient instruments were regularly inter-compared by bringing sensors or inlets to the same measurement height. The developed protocol resulted in an uncertainty on the order of 0.1 ppbv for 30-min averaged ozone gradients that were used for the ozone flux calculations. This protocol facilitated a lower sensitivity threshold for the ozone flux determination of ∼8 × 10−3μg m−2 s−1, respectively ∼0.01 cm s−1 for the ozone deposition velocity for typical environmental conditions encountered at Summit. Uncertainty in the 30-min ozone exchange measurements (evaluated by the Monte Carlo statistical approach) was on the order of 10−2 cm s−1. This uncertainty typically accounted to ~20–100% of the ozone exchange velocities that were determined. These measurements are among the most sensitive ozone deposition determinations reported to date. This flux experiment allowed for measurements of the relatively low ozone uptake rates encountered for polar snow, and thereby the study of their environmental and spring-versus-summer dependencies.

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